Inlet Air Heater Relay; Glow Plug Relay; Injection Pressure Regulator (Ipr) Valve - International VT 275 V6 Manual

Inlet Air Heater Relay

• The Inlet Air Heater (IAH) element is used
to improve cold start operation, reduce
emissions and white smoke, and improve
engine warm-up. The relay is mounted next
to the Power Distribution Center and is the
taller of the two relays. The IAH relay
receives battery power from the starter
power-feed terminal and the normally open
terminal connects to the element through
the harness. One end of the relay coil is
grounded through the engine 12-way
connector. The relay closes when the coil
receives voltage from the ECM.

Glow Plug Relay

• Glow plugs are used to improve cold
engine starting. Glow plug operation is
controlled by the ECM through the glow
plug relay. The glow plug relay is mounted
next to the Power Distribution Center and
is the shorter of the two relays. The relay
common terminal is connected by jumper
to the common terminal of the Inlet Air
Heater relay. The normally open terminal
connects to the glow plug harness. One
end of the relay coil is grounded through
the engine 12-way connector. The relay is
closed when the other end of the coil
receives voltage from the ECM.

Injection Pressure Regulator (IPR) Valve

• The IPR mounts to the high-pressure pump
and controls the amount of oil allowed to
drain from the high-pressure system.
When the ECM increases the IPR signal
duty cycle, the valve blocks the oil's path to
drain and pressure rises. When the ECM
reduces the duty cycle, a larger volume of
oil is allowed to drain from the system and
pressure is reduced. The valve contains a
pressure relief valve for the system that
opens if system pressure reaches 4500
psi. The IPR is protected by a heat shield
that must be reinstalled after servicing.
ELECTRONIC CONTROL SYSTEM
A A I I R R H H E E A A T T E E R R R R E E L L A A Y Y
A A I I R R H H E E A A T T E E R R R R E E L L A A Y Y
G G L L O O W W P P L L U U G G R R E E L L A A Y Y
G G L L O O W W P P L L U U G G R R E E L L A A Y Y
I I P P R R I I P P R R
International ® VT 275 V6 Engine
S S W W I I V V E E L L C C O O N N N N E E C C T T O O R R
S S W W I I V V E E L L C C O O N N N N E E C C T T O O R R
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